In the prior art stereoscopic video display systems, commercially available products have been expensive, and limited in their operations mode. Additionally, switching between two dimensional and three dimensional viewing modes has often required the changing of the video monitor setup within the computer. This is very time consuming and not easily accomplished by the average user. Therefore, while these three dimensional display glasses, or virtual reality glasses have been available in the past, they have met with limited success due to many of the limitations.
A typical set up is a personal computer having software for generating both left and right eye images on a video display. LCD shutter glasses are connected either to a port of the computer or to the display's V-sync signal for synchronizing the shutter state switching with the video scanning. A number of US patents in this field have issued to Lipton et al. (assigned to StereoGraphics Corporation), such as U.S. Pat. Nos. 4,523,226, 4,967,268, 5,181,133 and 5,572,250.
There are two basic modes of providing the right and left fields or images, namely either a composite image is generated having alternate lines for the right and left images respectively, or two separate images are generated by the computer in separate parts of the memory and the computer's video card is caused to "page flip" between the right and left images with each V-sync pulse. The video card must be able to switch reliably between the two pages at the speed of the V-sync of the video display monitor. When a composite image is used, the computer generates images for the left and right perspective and then blends the two images into one in the computer memory Since each image pixel in memory will appear as a pixel on the display on a discrete line of the display, it is possible to display the right and left images separately using an interlaced video display. An interlaced video display scans twice for each image, first for the odd lines and then for the even. The glasses are then triggered to switch with each V-sync pulse.
With non-interlaced video displays, which are common and often less expensive than interlaced video displays, the technique of using a single composite image containing interleaved right eye and left eye images cannot be used according to the prior art.
For convenience, the LCD glasses control unit may be connected to a dongle on the video port of the computer without connecting the control unit to another port of the computer. However, in the prior art, a part of the image is used for controlling and synchronizing the shutter glasses with the stereroscopic images being displayed. This leaves an undesirable visual effect on the 3D environment being viewed.